Historically, orthopedic surgeons and other specialists have worked with Plaster of Paris in the preparation of surgical casts. The problems associated with Plaster of Paris regarding its weight, susceptibility to water damage and insufficient x-ray opacity are well known in the art. These problems led to the development, and to a large extent, the replacement of Plaster of Paris with orthopedic bandages which utilize cast forming compositions and mixtures using water soluble vinyl monomers such as diacetone acrylamide (DAA) and N-isopropylacrylamide (N-IPA) wherein the monomers are polymerizable in the presence of water by means of an amine catalyst or a redox catalyst system that comprises an oxidation component and a reducing agent. Such orthopedic bandages are described, for example, in U.S. Pat. No. 3,630,194.
Also available as substitutes for Plaster of Paris are polyurethanes and cyanoacrylate esters. In addition, isocyanate prepolymer impregnated resins are available including those described in U.S. Pat. Nos. 4,411,262, 4,502,479 and 4,131,114. The bandages are hardened in a manner similar to the Plaster of Paris bandages by dipping the bandage into tap water which is then formed about the portion of the body to be immobilized or supported. Other prior art orthopedic bandages are found, for example, in U.S. Pat. Nos. 4,411,262, 4,376,438, 4,344,423, 4,502,479 and 4,433,680.
Typically, a prepolymer containing bandage is soaked in water prior to application to the body member. The wet bandage is then applied to the body member. After the bandage is applied, the cast is smoothed and molded with the applier's gloved hand and held at certain points until it hardens. Since the resins in the bandage are quite tacky until they cure completely, the protective gloves worn by the cast applier tend to stick to the bandage. This is disadvantageous as it can lead to delamination of the cast as layers of the tape pull apart from each other and the cast cannot be molded.
To alleviate this problem of "tackiness" in curable resin-coated bandages, Scholz et al. proposed in U.S. Pat. Nos. 4,667,661 and 4,773,937 that bandage sheets be pretreated by coating the surface of the bandage sheets with certain lubricants to reduce the kinetic coefficient of friction of such sheets to less than about 1.2. As noted in the Scholz et al. patents, the bandages treated with the described lubricants become very slippery, and molding of the cast becomes easier due to the reduced tackiness of the resin. The lubricant selected is from a variety of materials such as hydrophilic groups which are bonded to the curable resin or an additive which is incompatible with the curable resin, such as a surfactant, a polymer comprised of a plurality of hydrophilic groups or a polysiloxane.
While the Scholz et al. pre-coated sheets solve some of the tackiness problem, these sheets tend to be very slippery immediately after removal from the water bath used to activate the resin. The slipperiness makes it difficult for the applier of the cast to hold the tape securely and manipulate it into the form of a well fitting cast. The interlaminar strength of the final cast is also compromised due to the interference of the lubricant with the adhesive bonds which must form between the bandage layers.
A further attempt to solve the tackiness problem is included in U.S. Pat. No. 5,250,344 of Williamson et al. which proposes including microgranules of encapsulated lubricant in sizes ranging from 100 to 300 microns on only a portion of one side of a bandage substrate. The substrate is wound around a core for storage with the microgranules positioned such that they are on the end of the bandage closest to the core. The bandage substrate, including the microgranules, is then applied to the body member such that the end of the bandage substrate having the microgranules is applied as the outer portion of the cast. The applier of the cast then squeezes the outer portion of the bandage substrate, now formed into a cast, thereby bursting the microgranules and releasing lubricant over the entire surface of the cast. The lubricant released is then used to smooth the cast.
While Williamson et al. improve upon the Scholz et al. interlayer delamination problem, the applier of a cast using the Williamson et al. lubricated bandage still lacks adequate control over the quantity of the lubricant required in an individual case and the timing of the lubricant's release. In an optimal situation, the amount of lubricant available or the level of tackiness required at any given time and at different areas of the cast should be completely controlled by the applier, while he or she is molding the cast.
European Patent Applications Nos. 0 522 826 A1, 0 522 825 A1 and 0 522 824 A1 of Johnson & Johnson also attempted to solve the tackiness problem without affecting interlayer lamination of the cast by providing a glove having a dry, water-activatable lubricant material on the outside of the glove. While a lubricated glove may be helpful toward solving the tackiness and delamination problems, like Williamson et al., the applier still cannot adequately control the quantity of lubricant available during application. In addition, the lubricated gloves are not available in all necessary sizes and materials preferred by different surgeons and technicians.
One further solution is to provide lubricant separately in the form of a separate bar. An example of such a bar is the Poly Bithane.TM. No Tac bar of Carapace, Incorporated of Broken Arrow, Okla. While this helps to solve the lubricant control problem, it introduces a separate item into the cast bandage packaging, further adding to the costs of packaging and manufacture as well as necessitating disposal of the unused portion of the bar as an extra waste item.
Therefore, a need in the art still exists for an efficient, economical device and a method for applying a water-curable resin casting bandage which allows the applier to apply a cast without experiencing excessive tackiness while molding, smoothing and laminating the cast and which provides lubrication without unwanted delamination of the cast layers while the cast is hardening. Such a device and method should give the applier adequate control over the quantity and area of application of lubricant without needlessly limiting the applier's use of existing medical supplies, such as gloves, and without introducing extraneous items to the packaging of the casting bandage.